Age-specific mutation profiles and their prognostic implications in pediatric <i>KMT2A</i>-rearranged acute myeloid leukemia

Driver mutations in KMT2A-rearranged (KMT2A-r) have been identified in acute myeloid leukemia (AML); however, age-related differences in their frequency and prognostic factors remain unclear. In this study, we report age-specific mutation profiles and outcomes in pediatric patients with KMT2A-r AML. In 239 cases of KMT2A-r AML, infants (<1 year, n = 59) showed a significantly higher event-free survival (EFS) and overall survival (OS) compared with children (≥1 year, n = 180). Conversely, in 538 cases of non-KMT2A-r AML, infants exhibited a significantly lower EFS and OS than children. KMT2A::MLLT4 was only detected in children with KMT2A-r AML and was associated with a poor prognosis. In KMT2A-r AML, mutations in signaling pathway genes, such as KRAS, were frequently detected in infants and children. However, the frequency of non-signaling pathway mutations was significantly higher in children. Moreover, non-signaling pathway mutations had no significant effect on the prognosis in infants and children, whereas KRAS mutations were associated with poor prognosis in both groups. Multivariate analysis identified older age, a high white blood cell count, KMT2A::MLLT4, and KRAS mutations as independent adverse prognostic factors for both EFS and OS. These age-specific mutation profiles suggest distinct disease mechanisms across age groups and may help refine risk stratification and treatment strategies for pediatric KMT2A-r AML.